Multi-stage trim

ABSTRACT

A system including a valve trim having a plurality of flow paths, wherein each flow path of the plurality of flow paths includes a series of stages, and a plurality of expansion zones disposed in series with the series or stages, wherein each expansion zone of the plurality of expansion zones is disposed between a sequential set of adjacent upstream and downstream stages of the series of stages, wherein each expansion zone of the plurality of expansion zones is configured to flow a fluid in a direction that is generally transverse to directions of flow in both the adjacent-upstream stage and the adjacent-downstream stage, and wherein each expansion zone of the plurality of expansion zones is in line with one of the adjacent-upstream stage or the adjacent-downstream stage and offset from a different one of the corresponding adjacent-upstream stage or the adjacent-downstream stage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.12/669,039, entitled “Multi-Stage Trim”, filed on Jan. 13, 2010, whichis herein incorporated by reference, which claims priority to PCT PatentApplication No. PCT/IB08/53368, entitled “Multi-Stage Trim”, filed onAug. 21, 2008, which is herein incorporated by reference, which claimspriority to U.S. Provisional Patent Application No. 60/969,398, entitled“Multi-Stage Trim”, filed on Aug. 31, 2007, which is herein incorporatedby reference.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

In a variety of systems, it is often useful to lower the pressure of afluid. For example, pressure drops often occur during acquisition andprocessing of natural gas. At various stages of gas production, thenatural gas may achieve pressures that impede subsequent processing ofthe gas, thus it is desirable to flow the natural gas from ahigh-pressure region to a low-pressure region, dropping the gas pressurein transit.

Rapid drops in pressure, however, often cause a variety of problems.Flow across a large pressure gradient accelerates the fluid to a highvelocity, and the transition can cause damaging vibrations. In someinstances, the high-velocity fluid establishes a shockwave, or thinfluid layer in which a large energy transformation occurs. Theshockwaves emit noise, generate heat, and erode equipment. Thus,designers of fluid-handling systems strive to reduce fluid pressuregradually, so they avoid, or at least mitigate, shockwaves andvibrations.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a cross-section of an embodiment of a fluid-handling systemwith a trim;

FIG. 2 is a partial-cross-section of the trim;

FIG. 3 is a perspective view of a flow path through the trim;

FIG. 4 is a flow chart of an embodiment of a valve-designing processusing laser-doppler-anemometry (LDA); and

FIG. 5 is a diagram of an embodiment of a LDA test bench evaluating theflow path.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

FIG. 1 illustrates an example of a fluid-handling system 10 having atrim 12 that, in certain embodiments, addresses the above-mentionedproblems. The trim 12, as explained below, includes a plurality of flowpaths that gradually lower the pressure of a fluid flowing through thetrim 12. The flow paths include a series of stages, or constrictedpassages, and each stage lowers the fluid pressure by an amount that issubstantially smaller than the total pressure drop across the trim 12.Incrementally reducing the pressure is believed to prevent, or at leastmitigate, shockwaves and vibrations, because the smaller, incrementalpressure drops between stages do not accelerate the fluid as much as asingle, large pressure drop across a single-stage flow path.

Additionally, certain embodiments of the trim 12 are smaller, lessexpensive, and easier to manufacture than conventional designs, becauseembodiments of the trim 12 have relatively few stages and a relativelysimple geometry for a given overall pressure drop and a given amount ofacceptable erosion. The stages are sized based on the flow efficiency ofthe fluid passing through each stage, so the flow path expands moreaggressively and through fewer stages to the final stage size withoutany one stage conducting fluid at too high a velocity. Because there arefewer stages, the flow path is simpler, shorter, and less expensive tomanufacture. Additionally, the shorter flow path fits within smallertrims, thereby reducing material costs. Examples of the trim 12 aredescribed below, after describing some of the other components of thefluid-handling system 10.

The illustrated fluid-handling system 10 includes a choke valve 14, afluid source 16, and a fluid destination 18. The fluid source 16 and/orthe fluid destination 18 may be an offshore or onshore well, a pipeline,a refinery, a storage facility, a pressure vessel, a compressor, atanker, a liquefied-natural-gas terminal, or other source or destinationof a pressurized fluid. In this embodiment, the fluid source 16 is at ahigher pressure than the fluid destination 18. The pressure differencemay be greater than 1,000 psi, 5,000 psi, or 10,000 psi, depending onthe application, and the fluid from the source 16 may be air, steam,natural gas, water, oil, or other fluids.

In this embodiment, the choke valve 14 includes a housing 20, the trim12, a valve member 22, and an actuator 24. These components and theirfunctions are described below.

The illustrated housing 20 includes an upstream flange 25, a forwardhousing 26, a rear housing 28, a backing member 30, and a downstreamflange 36. The components of the housing 20 may be made of steel orother materials. The illustrated flanges 25 and 36 are secured to theforward housing 26 by welds 38 and 40. The backing member 30 is disposedinside both the forward housing 26 and the rear housing 28, and member30 is in contact with the trim 12 or an intermediary member. The backingmember 30 includes a chamber 31 that is generally complementary to thevalve member 22. Bolts 42 bias the rear housing 28 against the forwardhousing 26.

The forward housing 26 includes several features that, in the aggregate,define a flow path. At an upstream portion of the flow path, acontracting nozzle 44 meets the flange 25 and leads to an upstreammanifold 46. The upstream manifold 26, in this embodiment, surrounds thetrim 12 and defines a generally annular volume. The illustrated upstreammanifold 46 is generally concentric about a central axis 48 that extendsthrough the choke valve 14. Downstream from the manifold 46, the flowpath continues through the trim 12, dividing among a plurality of trimflow paths that are described below with reference to FIGS. 2 and 3. Thetrim flow paths collect in a downstream manifold 50 that is defined bythe interior of the trim 12. In this embodiment, the downstream manifold50 is a generally right, circular-cylindrical volume that is generallyconcentric about the central axis 48. Downstream from the manifold 50,the flow path continues into an expanding nozzle 52 that feeds into theflange 36.

The valve member 22 of FIG. 1 includes a shaft 54 and a sealing member56. The shaft 54 extends through, and is either permanently coupled orremoveably coupled to, the sealing member 56. The sealing member 56 hasa generally right, circular-cylindrical shape that is complementary tothe downstream manifold 50, and the sealing member 56 forms a sealingsurface with the interior of the trim 12. The sealing member 56 may bemade of an abrasion-resistant material, and the shaft 54 may be made ofsteel or other materials. The shaft 54 and the sealing member 56 aregenerally concentric about the central axis 48.

The illustrated actuator 24 is a manual actuator that includes a spacer58, an actuator shaft 60, a threaded portion 62, a nut 64, and a wheel66. In this embodiment, the actuator shaft 60 is coupled at one end tothe shaft 54. At the other end of the actuator shaft 60, the threadedportion 62 engages complementary threads in the nut 64 to form athreaded connection. The illustrated nut 64 is held in fixed relation tothe wheel 66, and the wheel 66 is rotationally coupled to the spacer 58.The spacer 58, the shaft 60, the nut 64, and the wheel 66 are generallyconcentric about the central axis 48.

In operation, an operator adjusts the flow through the choke valve 14 byrotating the wheel 66. As the wheel 66 rotates, it spins the nut 64around the threaded portion 62, while the actuator shaft 60 is preventedfrom rotating. The threaded coupling between the nut 64 and threadedportion 62 converts the rotation of the wheel 66 into a lineartranslation 68 of both the actuator shaft 60 and the valve member 22. Inthis embodiment, the valve member 22 may be described as having a singledegree of freedom.

Translation 68 of the valve member 22 changes the flow rate through thechoke valve 14. If the wheel 66 is rotated in a first direction, thesealing member 56 is pulled into the backing member 30, and the size ofthe downstream manifold 50 increases. A more-recessed sealing member 56obstructs fewer flow paths through the trim 12, thereby increasing theflow rate. Conversely, if the wheel 66 is rotated in a second, oppositedirection, the sealing member 56 pushes into the downstream manifold 50,and more flow paths through the trim 12 are obstructed by the sealingmember 56, thereby decreasing the flow rate through the choke valve 14.Thus, rotation of the wheel 66 modulates the flow rate through the chokevalve 14.

Other embodiments may have features different from those illustrated byFIG. 1. For instance, other embodiments may include other types ofactuators. The sealing member 56 may be adjusted by a hydraulic drive, apiston, an electric motor, a linear motor, or some other deviceconfigured to move the sealing member within the trim 12. In someembodiments, the sealing member 56 may be disposed in the upstreammanifold 46, and the sealing member 56 may have a generally tubularshape configured to slide over the trim 12. The illustrated choke valve14 is a 90-degree angled valve, because the valve outputs fluid flowingin a direction that is 90 degrees different from the direction in whichthe fluid is flowing when received, but other embodiments may include aninline valve that outputs fluid flowing in the same direction as thedirection in which fluid is flowing when received. It should also benoted that, in some applications, the fluid handling system 10 may notinclude a valve member 22. In these systems, the trim 12 still drops thepressure of a fluid flowing from the fluids source 16 to the fluiddestination 18, but the flow rate is not necessarily modulated by movinga valve member along the trim 12.

FIG. 2 depicts the trim 12. The term trim refers to a member configuredto remove kinetic energy from a fluid. In this embodiment, the trim 12includes a top plate 69, eight-intermediate plates 70, and a bottomplate 72. The top plate 69 and the bottom plate 72 include ledges 78 and80, respectively. The plates 69, 70, and 72 have a generally annularshape that is generally concentric about the central axis 48. A top face74 of each plate is generally parallel to a bottom face 76 of eachplate, and both faces 74 and 76 have a normal vector that is generallyparallel to the central axis 48. The plates 69, 70, and 72 may bemachined or otherwise formed from tungsten carbide, stainless steel, orother suitable materials.

The plates 69, 70, and 72 may be either permanently or removeablycoupled to one another. Permanently coupling the plates 69, 70, and 72is believed to increase the strength of the trim 12, and removeablycoupling the plates 69, 70, and 72 is believed to facilitate removal ofdebris that becomes trapped within the trim 12 during operation. In someembodiments, the trim 12 may be shrouded with a metal shield to protectthe trim 12 from debris carried by the fluid.

The plates 69, 70, and 72 include repeating collections of featuresreferred to as flow-path units 82. In this embodiment, the flow-pathunits 82 are repeated around the central axis 48 in a generallyrotationally-symmetric pattern, and each flow-path unit 82 includesfeatures of adjacent plates 69, 70, or 72. That is, both features on thebottom of a given plate 70 and features on the top of an adjacent plate70 are included in a given flow-path unit 82, so the flow-units 82 areformed by stacking the plates 69, 70, and 72. Each of the illustratedflow-path units 82 is generally identical to the other flow-path units82, but in other embodiments this may not be the case. For instance,features of the flow-path units 82, such as size, may vary along thecentral axis 48.

Within each flow-path unit 82, there are a plurality of cavities 84, 86,88, 90, 92, 94, and 96. As explained below, these cavities 84, 86, 88,90, 92, 94, and 96 combine to define a flow path that is described belowwith reference to FIG. 3. The cavities 84, 86, and 88 extend inward fromthe top face 74 of each plate, in a direction that is generally parallelto the central axis 48, and the cavities 90, 92, 94, and 96 extendupward from the bottom face 76, in a direction that is also generallyparallel to the central axis 48.

When the illustrated trim 12 is assembled, the cavities 84, 86, and 88in the top face 74 of a given plate 70 are not in fluid communicationwith the cavities 90, 92, 94, and 96 in the bottom face 76 of the sameplate 70. That is, in this embodiment, the flow does not cross entirelythrough any of the plates 69, 70, or 72 in an axial direction (i.e., adirection parallel to central axis 48), but rather the flow crosses backand forth between adjacent plates 70 in the manner described below withreference to FIG. 3. In other embodiments, however, the flow may crossentirely through one or more plates 70 in an axial direction.

Each of the flow-path units 82 includes an inlet 98 that receives aninflow 100 and an outlet 102 that emits an outflow 104, wherein eachflow-path unit 82 defines a flow path 106 generally extending in adirection (e.g., radial inward direction) from the inlet 98 to theoutlet 102, and each flow-path unit 82 has cavities (e.g., alternatingstages and expansion zones) arranged in alternating opposite lateraldirections and offsets relative to the direction from the inlet 98 tothe outlet 102 (see detailed arrangement of FIG. 3). As explained below,in this embodiment, each inlet 98 is in fluid communication with one andonly one outlet 102, but in other embodiments, one inlet 98 may be influid communication with multiple outlet 102 or vice versa.

Each of the intermediate plates 70 is generally identical, but in otherembodiments, different plates may cooperate to form the flow-path units82. For example, The flow-path units 82 may be formed by stacking fourplates: a lower, blank plate with no cavities; a plate with apertures inthe shape of cavities 84, 86, and 88 extending entirely through theplate; a plate with apertures in the shape of cavities 90, 92, 94, and96 extending entirely through the plate; and an upper, blank plate.

As mentioned above, the cavities 84, 86, 88, 90, 92, 94, and 96cooperate to define a flow path 106 illustrated by FIG. 3. The presentflow path 106 includes an inlet stage 108, six expansion zones 110, 112,114, 116, 118, and 120, five intermediate stages 122, 124, 126, 128, and130, and an outlet stage 132. These features of the flow path 106 aredefined by the cavities 84, 86, 88, 90, 92, 94, and 96 illustrated inFIG. 2. Specifically, the inlet stage 108 and the expansion zone 110 aredefined by the cavity 96; the intermediate stage 122 is defined by acavity 88; the expansion zones 112 and 114 and the intermediate stage124 are defined by the cavity 94; the intermediate stage 126 is definedby the cavity 86; the expansion zones 116 and 118 and the intermediatestage 128 are defined by the cavity 92; and the intermediate stage 130is defined by the cavity 84; and the expansion zone 120 and outlet stage132 are defined by the cavity 90. Thus, the flow path 106 is formed inboth the top of one plate 69 or 70 and the bottom of an adjacent plate70 or 72. As illustrated in FIG. 3, the flow path 106 extends in adirection (e.g., radial inward direction) from the inlet 98 (e.g., inletstage 108) to the outlet 102 (e.g., outlet stage 132), wherein the flowpath 106 has the stages (e.g., 122, 124, 126, 128, and 130) arranged inalternating opposite lateral directions (e.g., longitudinal axes of thestages) relative to the direction from the inlet 98 (e.g., inlet stage108) to the outlet 102 (e.g., outlet stage 132). In addition, the flowpath 106 has the expansion zones (e.g., 110, 112, 114, 116, 118, and120) arranged in alternating opposite lateral offsets relative to thedirection from the inlet 98 (e.g., inlet stage 108) to the outlet 102(e.g., outlet stage 132). As illustrated in FIGS. 2 and 3, the flow path106 is disposed in the trim 12 having an annular shape (e.g., annulartrim) about the central axis 48, and thus the alternating oppositelateral directions are alternating clockwise and counterclockwisedirections about the central axis 48, and the alternating oppositelateral offsets are alternating clockwise and counterclockwise offsets.

Each of the illustrated expansion zones 110, 112, 114, 116, 118, and 120has a generally right, circular-cylindrical shape with a generatrix thatis generally parallel to the central axis 48. (The term “generatrix”refers to a straight line that generates a surface by moving along aspecified path, e.g., a generatrix moved along a circular path forms acircular cylinder, and if the generatrix is normal to the plane in whichthe circle lies, it forms a right-circular cylinder.) Further, eachexpansion zone 110, 112, 114, 116, 118, and 120 may be characterized, inpart, by a diameter 134. The diameters 134 of the expansion zones 110,112, 114, 116, 118, and 120 progressively increase along the flow path106, with the diameter 134 of the expansion zone 120 being the largest,and the diameter 134 of the expansion zone 110 being the smallest. Insome embodiments, the corners of some or all of the expansion zones 110,112, 114, 116, 118, and 120 may have a chamfer or a fillet, depending onwhether the corner is an interior corner or an exterior corner. A height136 of the expansion zones 110, 112, 114, 116, 118, and 120 may begenerally uniform among these features and generally equal to a height138 of each of the stages 108, 122, 124, 126, 128, 130, 132. Otherembodiments, however, are not limited to these dimensionalrelationships. For example, the heights 136 and 138 may progressivelyincrease along the flow path 106.

Each of the stages 108, 122, 124, 126, 128, 130, and 132, in thisembodiment, has a generally cuboid shape, which defines a generallyrectangular cross-section 140. The area of the cross-section 140 isgenerally equal to the product of the stage height 138 and a stage width142. The stage height 138 and stage width 142 are both measured indirections that are perpendicular to the average direction of flowthrough the cross-section 140. The sides of the stages 108, 122, 124,126, 128, 130, and 132 are either generally perpendicular or generallyparallel to the central axis 48, and the corners may include a fillet.In other embodiments, one or more of the stages 108, 122, 124, 126, 128,130, and 132 may have a different, non-cuboid shape, such as acylindrical shape.

In this embodiment, the inlet stage 108, intermediate stages 124 and128, and outlet stage 132 are at generally the same axial position (asmeasured along the central axis 48) as the expansion zones 110, 112,114, 116, 118, and 120, and the intermediate stages 122, 126, and 130generally lie at an adjacent axial position. Adjacent intermediatestages 122, 124, 126, 128, and 130 define angles 144, and in someembodiments, these angles 144 are acute, e.g., between 5 and 85 degrees.

As previously noted, in this embodiment, the stage heights 138 aregenerally uniform among all of the stages 108, 122, 124, 126, 128, 130,and 132. The stage widths 142, however, increase progressively along theflow path 106, with the outlet stage 132 having the largest width 142,and the inlet stage having the smallest width 142. A corollary to thisis that the cross-sectional areas 140 also progressively increase alongthe flow path 106, with the inlet stage 108 having the smallestcross-sectional area 140, and the outlet stage 132 having the largestcross-sectional area 140.

In some embodiments, the cross-sectional area 140 of each stage may belarger than the cross-sectional area 104 of the adjacent, upstream stageby an amount that is based on the flow efficiency through variousportions of the flow path 106. The flow efficiency is defined as theflow rate through a structure divided by the pressure drop across thestructure, and the flow efficiency of stages that either upstream ordownstream of a given stage affect the pressure drop, and consequentlythe velocity, of the fluid flowing through the given stage. Flowefficiency and velocity of each stage may be determined with avalve-designing process described below with reference to FIGS. 4 and 5.In some embodiments, the ratio of cross-sectional areas 140 of adjacentstages may increase along the flow path 106, with the ratio of thecross-sectional area 140 of stage 124 to the cross-sectional area 140 ofstage 108 being the smallest, and the ratio of the cross-sectional area140 of stage 132 to the cross-sectional area 140 of stage 130 being thelargest. That is, the cross-sectional areas 140 may increase along theflow path 106 by a non-constant, increasing ratio.

The increase in consecutive feature sizes may be referred to as anexpansion ratio. The expansion ratio for a given stage is calculated bydividing its cross-sectional area 140 by the cross-sectional area 140 ofthe adjacent upstream stage. Thus, in some embodiments, the expansionratio of each stage 122, 124, 126, 128, 130, and 132 may progressivelyincrease along the flow path, with the outlet stage 132 having thelargest expansion ratio.

In operation, flow path 106 lowers the pressure of a fluid. As the fluidflows through each stage 108, 122, 124, 126, 128, 130, 132, the pressureof the fluid may drop and the volume and/or velocity of the fluid mayincrease relative to the previous stage, because as mentioned above, thecross-sectional area 140 of each stage is larger than thecross-sectional areas 140 of the upstream stages.

Between stages, the fluid enters the expansion zones 110, 112, 114, 116,118, 120. The expansion zones 110, 112, 114, 116, 118, 120 are believedto facilitate static pressure recovery, or the deceleration of a fluidto increase static pressure. In the expansion zones 110, 112, 114, 116,118, and 120, the aggregate flow undergoes two-90 degree bends 146 andthe 148. The first bend 146 is produced by the fluid turning in theexpansion zone and flowing downward, in the direction of the centralaxis 48, and the second bend 148 is from the fluid turning again andentering the next stage 122 to flow in a direction generallyperpendicular to the central axis 48. The sequence and orientation ofthe bends 146 and 148 depends on the expansion zone: in the expansionzones 110, 114, and 118, the fluid initially turns 90 degrees in adownward-axial direction before turning 90 degrees in a radial—orperpendicular to axial—direction; and in the expansion zones 112, 116,and 120, the fluid initially turns 90 degrees in an upward-axialdirection before turning 90 degrees in a radial direction. Thus, in thisembodiment, the fluid flows both axially and radially, and each turnremoves energy from the fluid.

The diameters 134 and widths 142 increase along the flow path 106 byamounts that depend both on parameters of the particularapplication—such as the type of fluid, the flow rate, and the overallpressure drop across the flow path 106—and the flow efficiency of thefluid flowing through the flow path 106. By sizing the diameters 134 andwidths 142 based on the flow efficiency, the flow path 106 can beexpanded over relatively few stages without giving rise to excessivevibrations or shockwaves. The amount of vibrations or shock waveintensity that are excessive will depend on parameters of the particularapplication, such as the desired life of the trim, the acceptable rateof trim material erosion, and the proximity of other equipment that issensitive to vibrations. A valve-designing process that accounts forflow efficiency is described below with reference to FIGS. 3, 4 and 5.

Sizing the diameters 134 and widths 142 according to flow efficiency isbelieved to offer certain advantages. The illustrated flow path 106exhibits relatively uniform pressure-drop ratios across each of thestages 108, 122, 124, 126, 128, 130, and 132. The pressure-drop ratiofor a given stage is calculated by taking the difference between thepressure of an adjacent, upstream stage and the pressure of an adjacent,downstream stage, and dividing the difference by the overall pressuredrop across the flow path 106. The uniformity of the pressure-dropratios may be characterized by a percent, pressure-drop-ratio variation,which is defined as 100 times the standard deviation of thepressure-drop ratios for each of the stages divided by the averagepressure-drop ratio for all of the stages. A low percent,pressure-drop-ratio variation indicates that the overall pressure dropacross the flow path 106 is evenly divided among the stages 108, 122,124, 126, 128, 130, 132. For example, certain embodiment with sevenstages may exhibit an average pressure-drop ratio near 0.3, a standarddeviation of pressure-drop ratio of 0.03, and a percent,pressure-drop-ratio variation of 9.3%. Some embodiments may becharacterized as having percent, pressure-drop-ratio variations lessthan 12%, 11%, 10%, or 9.5%.

Evenly allocating the overall pressure drop across the stages isbelieved to allow designers to simplify and shorten the flow path 106without giving rise to excessive vibrations or shockwaves. As describedin the background, damaging vibrations and shockwaves are caused bypressure gradients that are too large. Thus, the stage with the largestpressure-drop ratio, in part, determines how few stages the flow pathcan have without fluid flow generating vibrations and shockwaves. In theillustrated embodiment, none of these stages has a substantially largerpressure-drop ratio than the others, so none of the stages acts as aweak point. This means that fewer stages can perform a larger overallpressure drop without giving rise to excessive vibrations or shockwaves.Because it has relatively few stages for the size of the overallpressure drop it performs, the flow path 106 is relatively short, andbecause it is relatively short, the trim 12 consumes less material andcosts less. Further, each stage adds to the cost of machining the trim,so for this reason also, the trim 12 is believed to be less expensive tomanufacture. Finally, the trim 12 is believed to be less expensive tomaintain, because the flow path 106 has relatively few stages in whichdebris in the fluid might become trapped.

In other embodiments, the flow path 106 may have a different shape fromthe shape illustrated by FIG. 3. For example, other embodiments mayinclude more or fewer stages, depending on the fluid and the overallpressure drop. Generally, though, the larger the overall pressure drop,the more stages an embodiment will include.

FIG. 4 illustrates a valve-designing process 150. The illustratedprocess 150 begins with evaluating a valve design with computationalfluid dynamics (CFD). Evaluating a valve design may include modeling avalve with computer aided design (CAD) software and testing the modelwith CFD software. The design may be evaluated according to variouscriteria, such as the maximum fluid velocity, the flow efficiency, andvector streamlines. In some embodiments, a plurality of valve designsmay be evaluated, and the valve design with the best performance, e.g.,the lowest maximum velocity, is selected.

Next, the selected valve is provided, as illustrated by block 154. Insome embodiments, only a portion of the valve is provided for testing,for example, a flow path through a valve trim. The valve or the portionof the valve is, in some embodiments, provided by machining the flowpath in a material that facilitates testing, for example, a generallytranslucent material such as glass, Lucite, or Lexan.

After providing the valve, an aspect of the CFD evaluation may beverified with laser Doppler anemometry (LDA), as illustrated by block156. An example of an LDA test bench is described below with referenceto FIG. 5. During this step, an operator flows a test fluid through thevalve or portion of the valve that was provided in the previous step,and the LDA test bench measures the aspect of the CFD evaluation. Forinstance, the LDA test bench may measure a test-fluid pressure or atest-fluid velocity.

Based on the data from the LDA verification, it is determined whether toproduce the valve, as illustrated by block 158. Determining whether toproduce the valve may include determining whether the LDA results matchor corresponds with the CFD predictions. If the valve is produced, aplurality of instances of the valve are manufactured and installed influid-handling systems.

FIG. 5 illustrates an example of a LDA test bench 160. In thisembodiment, the LDA test bench 160 includes a sensor head 162 and asample-flow-path unit 164. The sensor head 162 includes two beam sources166 and 168, a light sensor 170, and two lenses 172 and 174. Each beamsource 166 and 168 emits a laser beam 176 and 178, respectively. Thesebeams 176 and 178 are focused by the lens 172 on a measurement volume180 inside the sample-flow-path unit 164. The sample-flow-path unit 164,in this embodiment, is made from a translucent material, such as thosediscussed above, and includes a flow path 182 conducting a test fluid.The test fluid is air laden with oil or smoke particles.

In operation, the particles and the test fluid flow through themeasurement volume 180, and the illuminated particles reflect light thatindicates the velocity of the particles. The effect of the particles issensed by the light sensor 170, which is configured to calculate a fluidvelocity within the measurement volume 180.

In this embodiment, as indicated by arrow 184, the sensor head 162 isconfigured to raster the measurement volume 180 through substantiallythe entire flow path 182 to map fluid velocities within the flow path182. From this map of fluid velocities, various aspects of the flow path182 may be evaluated, such as the maximum velocity of fluid in the flowpath 182 or the pressure drop across portions of the flow path 182.

Employing the LDA test bench 160 in the execution of the process 150 isbelieved to yield valve designs that, relative to conventionallydesigned valves, have a shorter flow path for a given fluid flowedacross a given pressure drop at a given flow rate without exceeding agiven maximum acceptable rate erosion or a given noise maximum. The LDAtest bench 160 validates predictions from CFD with empirical data, sothe valve design can be adjusted based on actual flow conditions beforethe valve design is released to production.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A system, comprising: a valve trim having aplurality of flow paths, wherein each flow path of the plurality of flowpaths comprises: an inlet; an outlet; a series of stages disposedbetween the inlet and the outlet; and a plurality of expansion zonesdisposed in series with the series of stages between the inlet and theoutlet, wherein each expansion zone of the plurality of expansion zonesis disposed between a sequential set of adjacent upstream and downstreamstages of the series of stages, wherein each expansion zone of theplurality of expansion zones is configured to flow a fluid in adirection that is generally transverse to directions of flow in both theadjacent upstream stage and the adjacent downstream stage, wherein eachexpansion zone of the plurality of expansion zones is sized larger thana first cross-sectional area of the adjacent upstream stage and a secondcross-sectional area of the adjacent downstream stage, wherein eachexpansion zone of the plurality of expansion zones has a total heightfrom a first end to a second end of the respective expansion zone,wherein the total height of each expansion zone of the plurality ofexpansion zones vertically overlaps with a first height of one of theadjacent upstream stage or the adjacent downstream stage and does notvertically overlap with a second height of a different one of thecorresponding adjacent upstream stage or the adjacent downstream stage,wherein the total height, the first height, and the second height aremeasured perpendicular to the directions of flow, wherein the pluralityof expansion zones progressively increase in size along each of the flowpaths, and wherein at least one of the plurality of flow paths comprisesstages in the series of stages with generally rectangular cross-sectionsthat progressively increase in height.
 2. The system of claim 1, whereinthe total height of each expansion zone of the plurality of expansionzones and the second height of the different one of the correspondingadjacent upstream stage or the adjacent downstream stage are verticallystacked with one completely above the other.
 3. The system of claim 1,wherein at least one flow path of the plurality of flow paths includesstages in the series of stages that progressively increase in sizeaccording to a non-constant increasing ratio.
 4. The system of claim 1,wherein at least one stage of the series of stages defines a generallycuboid volume.
 5. The system of claim 1, wherein at least one of theplurality of expansion zones defines a generally cylindrical volume. 6.The system of claim 1, wherein at least some adjacent upstream anddownstream stages of the series of stages have respective first andsecond central longitudinal axes extending in respective first andsecond directions that form acute angles between each other.
 7. Thesystem of claim 1, wherein the valve trim has a generally tubular shapedisposed about a central axis, the inlet comprises a radial inlet, andthe outlet comprises a radial outlet.
 8. The system of claim 1, whereinthe valve trim has a generally tubular shape disposed about a centralaxis, and each stage of the series of stages extends parallel to a planethat is generally perpendicular to the central axis.
 9. The system ofclaim 1, wherein the valve trim comprises a plurality of plates, andadjacent upstream and downstream stages of the series of stages aredisposed in different plates of the plurality of plates.
 10. The systemof claim 1, comprising a choke valve having the valve trim.
 11. Thesystem of claim 10, comprising a mineral deposit, a well, a pressurevessel, a pipeline, a storage facility, a mineral processing facility, arefinery, a mineral extraction system, a christmas tree, or acombination thereof, coupled to the choke valve.
 12. The system of claim10, wherein the choke valve comprises: a housing that defines anupstream manifold having the valve trim; a valve member configured totranslate through the valve trim and adjust a flow rate through thechoke valve; and an actuator configured to move the valve member. 13.The system of claim 1, wherein a pressure drop between each sequentialset of adjacent upstream and downstream stages in the series of stagesis less than 12%.
 14. The system of claim 1, wherein the series ofstages each define a generally cuboid volume and the plurality ofexpansion zones each define a generally cylindrical volume, wherein thetotal height of the generally cylindrical volume of each expansion zoneof the plurality of expansion zones vertically overlaps with the firstheight of one of the generally cuboid volumes of the adjacent upstreamstage or the adjacent downstream stage and does not vertically overlapwith the second height of a different one of the generally cuboidvolumes of the corresponding adjacent upstream stage or the adjacentdownstream stage.
 15. The system of claim 1, wherein the total height ofan expansion zone of the plurality of expansion zones is less thananother total height of the first and second heights of the adjacentupstream stage and the adjacent downstream stage of the series ofstages.
 16. The system of claim 15, wherein the total height issubstantially equal to one of the first or second heights.
 17. Thesystem of claim 1, wherein the series of stages is arranged inalternating opposite directions relative to a direction from the inletto the outlet of the respective flow path, and the plurality ofexpansion zones is arranged on alternating opposite sides with respectto the direction from the inlet to the outlet of the respective flowpath.
 18. The system of claim 17, wherein each stage of the series ofstages has at least one flat side extending along the respective stageto define a stage flow path, and each expansion zone of the plurality ofexpansion zones has a curved side extending over the total height fromthe first end to the second end of the respective expansion zone todefine an expansion flow path.
 19. The system of claim 17, wherein theseries of stages is arranged in the alternating opposite directions atacute angles to define a series of V-shaped paths, and each V-shapedpath of the series of V-shaped paths has an expansion zone of theplurality of expansion zones disposed between the adjacent upstreamstage and the adjacent downstream stage of the series of stages.
 20. Thesystem of claim 19, wherein the series of V-shaped paths defines azigzagging path.
 21. A system, comprising: a valve trim having aplurality of flow paths, wherein each flow path of the plurality of flowpaths comprises: an inlet; an outlet; a series of stages between theinlet and the outlet, wherein each stage of the series of stages has atleast one flat side extending along an axis of the respective stage todefine a stage flow path; and a plurality of expansion zones disposed inseries with the series of stages between the inlet and the outlet,wherein each expansion zone of the plurality of expansion zones has acurved side extending along an axis of the respective expansion zone todefine an expansion flow path, wherein each expansion zone of theplurality of expansion zones is disposed between a sequential set ofadjacent upstream and downstream stages of the series of stages, whereineach expansion zone of the plurality of expansion zones is configured toflow a fluid in a direction that is generally transverse to directionsof flow in both the adjacent upstream stage and the adjacent downstreamstage, and wherein at least one of the plurality of flow paths comprisesstages in the series of stages with generally rectangular cross-sectionsthat progressively increase in height.
 22. The system of claim 21,wherein the at least one flat side of each stage of the series of stagescomprises a plurality of flat sides, and the curved side of eachexpansion zone of the plurality of expansion zones comprises an annularside.
 23. A system, comprising: a valve trim having a plurality of flowpaths, wherein each flow path of the plurality of flow paths comprises:a series of stages; and a plurality of expansion zones disposed inseries with the series of stages, wherein each expansion zone of theplurality of expansion zones is disposed between a sequential set ofadjacent upstream and downstream stages of the series of stages, whereineach expansion zone of the plurality of expansion zones is configured toflow a fluid in a direction that is generally transverse to directionsof flow in both the adjacent upstream stage and the adjacent downstreamstage, wherein each expansion zone of the plurality of expansion zonesis in line with one of the adjacent upstream stage or the adjacentdownstream stage and offset from a different one of the correspondingadjacent upstream stage or the adjacent downstream stage, wherein atleast one of the plurality of flow paths comprises stages in the seriesof stages with generally rectangular cross-sections that progressivelyincrease in height.